Hi ^_^

Well I've had a few Tenchi Muyo in Love cels pass through
my hands and they have all been standard sized. Also she
does wear a school uniform in Pretty Sami, but it is a different
one than in the movie (not blue either)  The only other time
I can remember her wearing a fuku is during the Time and Space
Adventures and that one was plaid. I hope I'm not missing
something, but it is almost a sure bet that your cel is
from TMiL

Emika >^.^<